제출한 정답
SELECT REST_INFO.REST_ID, REST_NAME, FOOD_TYPE, FAVORITES, ADDRESS, ROUND(AVG(REVIEW_SCORE),2)as SCORE
FROM REST_REVIEW JOIN REST_INFO ON REST_REVIEW.REST_ID = REST_INFO.REST_ID
WHERE SUBSTR(ADDRESS,1,5) = '서울특별시' OR SUBSTR(ADDRESS,1,3) = '서울시'
GROUP BY REST_ID
ORDER BY SCORE DESC, FAVORITES DESC
수정하면 좋을 부분
ADDRESS LIKE '서울%'
로 작성했으면 더 좋을 듯 함.